The Woriey project examines molecular mechanisms of activity-dependent synaptic plasticity that contribute to drug addiction. Aim 1 will use newly developed mouse models that afford in vivo regulation of expression of the immediate eariy gene (IEG) Rhebl to examine how signaling of the mammalian target of rapamycin (mTOR) controls dynamic protein translation. In work supported by this grant, we have demonstrated that Rhebl is essential and sufficient to activate mTORCI in vivo, and have established viable mouse models that either conditionally delete Rhebl or express an activated Rhebl transgene (Zou et al., 2011). To explore the role of mTOR in protein translation, we will process brains of Rhebl transgenic mice to isolate mRNAs that are associated with polyribosomes or ribosomes in the process of translation initiation, and identify those RNA sequences that are protected from RNase digestion using RNA seq (Ingolia et al., 2009). Studies will test the hypothesis that mTOR controls translation of a specific set of brain mRNAs, and will test the scanning hypothesis for translation initiation. Aim 2 will focus on mTOR-dependent proteins that are generated in neurons, and that regulate myelination in the CNS. Myelination is known to be dependent on neural activity and is disrupted in patients with drug addiction, however the molecular basis ofthis process is unknown. Rhebl transgenic mice show prominent changes in myelination (Zou et al., 2011) and preliminary studies indicate a role for neuron-generated proteins that control the differentiation of oligodendrites and their generation of myelin proteins. Information from Aim 1 mRNA analysis and direct assays of protein expression will generate candidate proteins, and these will be tested using in vivo assays for effects on myelination. Aim 3 will explore the role of a novel protein family termed LanCLI in regulation of activity- dependent reactive oxygen species (ROS). LanCLI is regulated as an lEG and is highly expressed in normal brain. We have developed models that conditionally delete LanCLI gene or express LanCLI transgene in brain and we will use these models to test the hypothesis that dynamic expression of LanCLI is essential for normal synaptic plasticity and cocaine-evoked plasticity.